1. And Muscles of the Head and Neck
The Naming of Muscles
And Muscles of the Head and Neck

2. Naming Muscles Muscles are named according to:
Location (frontalis – forehead)
Size (gluteus maximus)
Direction (external abdominal oblique)
Number of origins (biceps femoris)
Location of origin and insertion (sternocleidomastoid)
Action (flexor carpi ulnaris)
Shape (deltoid – triangular)

3. Muscles of the Head

4. There are 656 muscles in the human body.
327 of these muscles are in antagonistic pairs (654)
2 muscles are unpaired
orbicularis oris
diaphragm

5. Head Muscles Have many specific functions.
Are grouped into 2 categories:
1. Facial muscles
Provide movement for facial expressions
Are unique in that they insert into soft tissues such as other muscles or skin
2. Chewing muscles
Control the mandible for mastication
Begin the breakdown of food in the digestive process

6. Facial Muscles Frontalis Covers the frontal bone
Starts at the cranial aponeurosis (a thin sheath of connective tissue that cover the crown of the skull) and inserts at the skin of the eyebrows.
Functions to raise eyebrows and wrinkle the forehead

7. Occipitalis Covers the posterior portion of the cranium.
Starts at the back part of the cranial aponeurosis and connect to the skin at the back of the head.
Functions to pull the scalp posteriorly (used for wiggling your ears)

8. Orbicularis Oculi
Has fibers that run in a circular pattern around the eye. Also lies underneath the eyebrows.
Functions to close your eyes, squint, blink, and wink. Also tightens the skin on the forehead.

9. Orbicularis Oris
A circular muscle that surround the opening of the mouth.
Functions to close and compress the lips. Also allows you to protrude your lips.
AKA the “kissing” muscle

10. Muscles that move the orbicularis oris
Levator labii superioris nasi
Levator labii superioris
Zygomaticus minor
Zygomaticus major
Levator anguli superioris
Orbibularis oris
Node (corner of mouth)
Risorius
Platysma
Despressor anguli oris
Depressor labii inferioris
Mentalis

11. Buccinator
A horizontal muscle that runs across the cheek starts at the lateral angle of the mandible and inserts into the orbicularis oris.
Functions to flatten the cheek (when whistling or blowing a trumpet).
Also somewhat involved in chewing. It compresses the cheek to hold food in between the teeth during chewing.

13. Zygomaticus
Extends from the corner of the mouth to the cheekbone at a diagonal.
This muscle has two bodies:
major the larger of the two, found more laterally
minor the smaller of the two, found more medially
Functions to raise the corners of the mouth.
Is often referred to as the “smiling” muscle.

14. zygomaticus

15. Depressor Anguli Oris
Originates along the side of the chin and tapers to inserts at the corner (node) of the orbicularis oris.
Functions to depress or pull down the corners of the mouth.

16. Nasalis Two sets of muscles located over the nasal bones.
One is lateral
One is vertical
Functions to close and open the nasal opening.
Allows you to flare and close your nostrils.

17. Muscles of Mastication

18. Masseter
Runs from the zygomatic process of the temporal bone to the mandible.
Covers the lateral surface of the angle of the lower jaw.
Is the primary muscle involved in closing the jaw; does so by elevating the mandible.

19. Temporalis A fan-shaped muscle overlying the temporal bone.
Passes underneath the zygomatic process and inserts into the mandible.
Acts as a synergist of the masseter.
Functions to raise the jaw and draw the jaw backward.

20. Neck Muscles
For the most part, these muscles move the head and the shoulder girdle.
These muscles cause the head:
Extension
Flexion
Rotation

21. Platysma
A broad, sheet-like muscle that covers the anterolateral surface of the neck.
Orginates from the connective tissue covering the chest muscles and inserts into the area around the mouth.
Functions to pull the lower jaw inferiorly and backward.

23. Sternocleidomastoid
Paired muscles found diagonally on each side of the neck.
Originates at two places:
from the sternum
from the clavicle
The heads fuse and insert into the mastoid process of the temporal bone.
If both contract, functions to flex the neck.
If one contracts, the head is rotated.

25. Identify the muscles that are being used in the following facial expressions.